Tennis ball throwing machine
Patent 3990426 Issued on November 9, 1976. Estimated Expiration Date: 
November 9, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
November 9, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesClaimsI claim:1. A pneumatic tennis ball throwing machine comprising a pipe, a ball-ejecting barrel of lesser effective cross section than the pipe, means for connecting one end of the barrel to the pipe, means for forcing a substantially continuous stream of air in one direction through said pipe and thence through the barrel, a ball feed device, and means for introducing balls from said feed device into said air stream upstream of said one end of the barrel, said means comprising a ball port through a curved wall of the pipe, which wall is concave on the inner side thereof, a flexible flap valve means for closing said ball port, means mounting said flexible flap valve onto a portion of the inner sideof said pipe which lies below and at one side of said port, said flap valve means being characterized in that it is normally at least partly open to provide an air bleed passage therepast to the atmosphere and being sufficiently flexible to conform incurvature to the curved inner wall of the pipe so as to close said ball port in response to back pressure resulting from at least partial choking by the ball of said air stream as the ball moves with the airstream from the pipe towards the barrel. 2. A pneumatic ball throwing machine as claimed in claim 1, the means for connecting the pipe to one end of the barrel comprising a second pipe of lesser effective cross-sectional area than the first mentioned pipe and of greater effective crosssectional area than the barrel. 3. A ball throwing machine, comprising a body having an upwardly facing ball entry port therein, a ball magazine on said body, said magazine having a normally horizontal elongate open bottom through which a row of balls may emerge downwardly by gravity, an endless flexible conveyor belt having a normally horizontal upper run disposed beneath the open bottom of the magazine and one end of which is disposed towards the ball entry port, and means for driving said flexible conveyor whereby to movetowards the ball port the balls which have emerged from said magazine, means adjacent said end of said flexible conveyor for imposing an impedance upon said balls whereby to effect a time delay between successive balls as they move along a path from said conveyor belt run towards said ball port, said means for imposing an impedance on said balls comprising an element extending along said path and forming a squeeze pass therefore, said element comprising an elongate member overlying said path and having a resilient member on the underside thereof for engaging said balls whereby said balls roll along said resilient member as they move along said path. 4. A ball throwing machine as claimed in claim 3, said resilient member having a downwardly facing friction surface. 5. A pneumatic tennis ball throwing machine comprising a pipe, an air intake, air impelling means for forcing air in one direction from said intake along a path through the pipe, a ball-projecting barrel of lesser effective cross section thansaid pipe, air conduit means for connecting the barrel to the pipe, said air conduit means and said barrel constituting a normally open outlet for said air, absent a ball therein, a ball port through a wall of the pipe alongside said path, which wall iscurved on the inner side thereof, a normally open generally flat flexible flap valve means, and pivot means mounting said flexible flap valve means on the inner side of said pipe at a location at one side of said port, said pivot means providing forswinging movement of said flexible flap valve about an axis which extends in the direction of air flow past said port from said intake towards said conduit means, said flap valve means being sufficiently flexible to conform to the curvature of the pipearound said ball port in response to back pressure prevailing in said pipe upon choking of said outlet. 6. In combination a tennis ball throwing machine comprising a body, a device in said body for projecting a tennis ball, and a magazine removably mounted on said body for supplying balls to said device, said body having a laterally spaced pair ofmagazine mounting elements thereof providing upwardly convex surfaces, said magazine comprising a pair of panels having upper and lower portions, mounting means for normally maintaining said panels in substantially parallel vertical planes spaced fromone another a predetermined distance, said mounting means providing connections between the upper portions of said panels while permitting the lower portions thereof to spread apart from one another, and lip means projecting inwardly from lower edgeportions of said panels, said mounting means being characterized by springiness whereby when said lip means are pressed downwardly over a tennis ball, they spring apart to permit a ball to squeeze therebetween, the span of said upwardly convex surfaceson said elements being sufficiently great that when the lip means are pressed downwardly thereon, said lip means are thereby spread apart more than said predetermined distance. 7. The combination claimed in claim 6, the means for maintaining said side wall comprising two pair of rods normally vertically disposed, elements for holding the upper ends of the rods in each pair together, each pair of rods and theirassociated one of said holding elements forming inverted U's, spacer means for maintaining said elements in spaced relation, said panels each having opposite end edges connected to corresponding rods of each pair, said lip means comprising a pair of rodsconnecting the lower ends of corresponding rods of each pair. 8. The combination claimed in claim 7, said panels being of transparent material. |
